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Numerical investigations on motorcycle wheels are described, in order to point out their aerodynamic characteristics and their influence on the global aerodynamic behavior of the motorcycles. The trials studied the development of the design of the front mud-guard in a commercial motorcycle, that showed an undesirable lift effect during on-road and wind tunnel tests. The functionality of the mud-guard was checked, varying its shape and dimensions, in order to reduce the lift effect and eventually to improve the whole behavior of the motorcycle.

In Formula Student competitions, the active adaptation of the aerodynamic components to the current race track conditions can significantly enhance the overall dynamic performance of the car. Due to the abundant low-speed corners, angles of attack of fixed aerodynamic components are usually exaggerated, preventing the car from achieving higher acceleration capabilities due to induced drag. This issue can be tackled by introducing an active drag reduction system (DRS). In this work, a strategy for performing iterative numerical simulations is proposed, with the goal of obtaining a range of different configurations suitable for certain track conditions. Specifically, the case of lowest drag is exploited. Different macros were developed to couple the utilization of computational fluid dynamics tools for aerodynamic analysis with an extensive iterative process with minimal user interference. An initial mesh refinement study was conducted.

In this work a numerical method for the design of components submitted to severe cyclic thermomechanical loading is developed. This tool is based on a Finite Element (FE) analysis. In a first part the temperature distribution is obtained and used in the second part for the mechanical computation. The analyses use the description of the geometry of the part, a precise information of the thermal properties, an appropriate behavior of the material at low and high temperature and a good assessment of the boundary conditions (heat transfer coefficients, contact, …). This method is applied to asses the low cycle fatigue design of a diesel turbo-charged exhaust manifold in cast iron. These calculations, failure location and lifetime estimation, obtained on two versions of this component, are compared to experimental data. The results show a good agreement in terms of critical zones location and of lifetime comparison in both versions and permit thus to classify the versions.

The paper describes a predictive tool for the determination of air and coolant temperatures and heat exchange resulting from the operation of heat exchangers, e.g., radiator or air-conditioner condenser in the underhood of automotive engines. The paper describes a detailed computational model where both the fluid streams are numerically solved and the phase change of the refrigerant is taken into account in a condenser simulation. An actual underhood simulation with interactions with a radiator is presented. A numerical simulation for a condenser is also presented. Reasonable agreement is shown with the test data.

In rally competition cars, the safety of vehicle occupants is currently projected without precise regulations. In order to reduce design time and control testing costs, finite element approaches and numerical comparisons between different solutions are used to reduce costs and improve performance. Within, a methodology and case study for attainting this goal are proposed. Using a numerical model of a rally car, different materials are compared and design indications are noted. A numerical non-linear model of half of a competition car roll-cage and its related door parts is built, in order to simulate the dynamics of lateral impact with a tree. Several numerical tests are conducted with the different absorbent materials and with different design solutions. Based on the deformation energy and acceleration of the roll-cage structure, an evaluation criterion is proposed.

It is challenging to develop highly efficient and clean engines while meeting user expectations in terms of performance, comfort, and drivability. One of the critical aspects in this regard is combustion noise control. Combustion noise accounts for about 40 percent of the overall engine noise in typical turbocharged diesel engines. The experimental investigation of noise generation is difficult due to its inherent complexity and measurement limitations. Therefore, it is important to develop efficient numerical strategies in order to gain a better understanding of the combustion noise mechanisms. In this work, a novel methodology was developed, combining computational fluid dynamics (CFD) modeling and genetic algorithm (GA) technique to optimize the combustion system hardware design of a high-speed direct injection (HSDI) diesel engine, with respect to various emissions and performance targets including combustion noise.

To ensure ride comfort, the dynamic characteristics, such as natural frequencies, of a vehicle is often tuned to a specific value by managing the magnitude and location of some masses and/or configuration of stiffeners without sacrificing the structural strength and overall fuel performance of the vehicle. We first formulate the mathematical statement of the problem in a constrained eigenvalue form. Optimal solutions are sought using various finite element techniques. A novel methodology involving genetic algorithm and Newton’s iterative method is developed to solve the constrained eigenvalue problems. Several examples, including discrete and continuous systems, are presented to demonstrate the effectiveness and accuracy of the proposed methodology. The strategy of managing the mass location and distribution to target a preferred natural frequency or frequencies is given in the conclusion.

Seating and ride comfort for a driver during a test drive are the vital factors when making the decision for a new vehicle. Typically, big test series with test drivers are carried out for static and dynamic seat comfort in the lab and for riding comfort on specified road profiles considering all relevant scenarios. The amount of subjectivity involved in the evaluation of the comfort reduces the reliability of such studies to serve as a basis for design. Numerical simulations represent a cost-effective, yet highly reliable method to evaluate the seating and the ride comfort. There exist several approaches using FEA (finite element analysis) for seating comfort and MBS (multi body system) analysis for riding comfort. Although both parts influence each other there exist no real interfaces between the different types of analysis. This paper presents a numerical approach to the analysis of the impact of vibrations on the human body arising from real excitations of the whole vehicle.

Information stored in the electronic control modules (ECM) of modern class 8 tractors is a valuable tool to accident reconstruction, but must be properly interpreted. The stored ECM speed data is driveshaft speed. To determine the road speed, the investigator must determine if braking occurred. The level of braking can be estimated from the data and computation of the road speed from the driveshaft speed can be performed by estimating the tire slip. Failure to determine the road speed can result in substantial error in velocity and travel distance estimates. Using realistic models it is shown that proper numerical integration techniques will produce negligible error in highway speed braking distances.

Natural gas has been used in spark-ignition (SI) engines of natural gas vehicles (NGVs) due to its resource availability and stable price compared to gasoline. It has the potential to reduce carbon monoxide emissions from the SI engines due to its high hydrogen-to-carbon ratio. However, short running distance is an issue of the NGVs. In this work, methodologies to improve the fuel economy of a heavy-duty commercial truck under the Japanese Heavy-Duty Driving Cycle (JE05) is proposed by numerical 1D-CFD modeling. The main objective is a comparative analysis to find an optimal fuel economy under three variable mechanisms, variable valve timing (VVT), variable valve actuation (VVA), and variable compression ratio (VCR). Experimental data are taken from a six-cylinder turbocharged SI engine fueled by city gas 13A. The 9.83 L production engine is a CR11 type with a multi-point injection system operated under a stoichiometric mixture.

This report shows the methods, which AVL uses for the calculation of gear box noise. The analysis of the gear box structure (housing) is done using finite element method (FEM), thereby the natural frequencies are calculated as well as forced vibrations. As input for the FE calculation of the forced vibrations, the dynamic bearing forces of the shafts in the gear box or the dynamic tooth mesh are used. These forces are determined using the MBS (multi body system) software GTDYN, considering the torsional vibrations as well as axial and bending vibrations. Several examples of calculation results for the investigation of the gear dynamics are shown within the scope of this report.

Cavitation, the study of formation, growth, and collapse of vapor cavities in the coolant jacket adjacent to diesel engine cylinder liners is an area of concern for diesel engine builders and users. Prior experimental work provides insight into parameters such as temperature and pressure. A commonly used bench test has been found not to correlate well with field testing. Also, field testing is very time consuming and costly. The 250 hour engine dynamometer coolant test in the industry costs over $60,000. Therefore, use of mathematical models for sorting out coolants is used, to study effects of coolant properties such as viscosity and surface tension on liner cavitation. Jet velocity at the time of implosion of the bubble is considered as a mechanism to quantify cavitation damage potential near a rigid wall. A model calculating jet velocity at the time of bubble collapse near a finite plate is determined using a commercial boundary element code, 2DynaFS.

Most research on the thumb kinematics has focused on the local trapezo-metacarpal movement independently of the hand. In the clinical area, these studies can be sufficient. However, when the simulation of the hand movement and prehensile tasks with numerical dummies is needed, the thumb has to be considered as an integral part of the hand so a study in this direction proves to be essential. The objective of the present study is to analyze the kinematics of the thumb in relation to the hand (i.e. from the wrist’s joint). This paper proposes a four-link kinematic model of the thumb with 5 degrees of freedom (DOF) for a better representation of the opposition of the thumb with the other fingers. The interphalangeal and the metacarpophalangeal joints of the thumb have 1 flexion/extension DOF each and the carpo-metacarpophalangeal has 3 DOF (flexion/extension, abduction/adduction and rotation).

Catalyst simulation, which can analyze the complicated reaction pathway of exhaust gas purifications and identify the rate-determining step, is an essential tool in the development of catalyst materials. This requires an elementary reaction model which describes the detailed processes, i.e. adsorption, decomposition, and others. In our previous work, the elementary reaction model on Pt/CeO2 catalyst was constructed. In this study, we focused on extending the Zeolite catalyst and including the gas diffusivity through the catalyst layer. The reaction rate of a Zeolite catalyst was expressed by an Arrhenius equation, and the elementary reaction model was composed of 17 reactions. Each Arrhenius parameter was optimized by the catalytic activity measurements. The constructed model was validated with NOx conversion in cyclic experiments which were repeated with Lean phase (NOx adsorption) and Rich phase (NOx reduction).

To evaluate the relationship between the exhaust gas purification performance and the catalyst pore properties related to gas diffusion, an elementary reaction model was combined with gas diffusion into catalyst pores, referred to as the pseudo-2D gas diffusion/reaction model. It was constructed for Pt/Al2O3 + CeO2 catalyst as lean NOx catalyst. The gas diffusion was described as macro pore diffusion between the catalyst particles and meso pore diffusion within the particle. The kinetic model was composed of 26 reactions of NO/CO/O2 chemistry including 17 Pt/Al2O3 catalyst reactions and 9 CeO2 reactions. Arrhenius parameters were optimized using activity measurement results from various catalysts with various pore properties, meso pore volume and diameter, macro pore volume and diameter, particle size, and washcoat thickness. Good agreement was achieved between the measured and calculated values.

The forming behaviors of tailor-welded blanks (TWBs) have been widely studied since they were first developed as a way of using collectible offal. A typical TWB is composed of several base metals, which might have different mechanical properties as well as thickness. Moreover, a TWB contains heat-affected zone (HAZ) which has quite different mechanical properties as base materials do. Little published information on HAZ is available up to now, especially its numerical modeling. It is not clear how much HAZ affects the formability and the springback of TWB. In this paper, the mechanical properties of HAZ are determined from hardness test and tensile test. The eccentric load applied in tensile test is essential for decomposing the properties of the base materials and the HAZ. Various finite element modes for TWB are presented. An appropriate model based on the considerations of accuracy and computing efficiency is suggested.

This SAE Aerospace Information Report (AIR) has been written for individuals associated with ground level testing of turbofan and turbojet engines, and particularly for those who might be interested in investigating steady-state performance characteristics of a new test cell design or of proposed modifications to an existing test cell by means of numerical modeling and simulation. It is not the intent of this standard to provide specific test cell design recommendations, which are covered in the reference documentation.

EGR coolers are mainly used on diesel engines to reduce intake charge temperature and thus reduce emissions of NOx and PM. Soot and hydrocarbon deposition in the EGR cooler reduces heat transfer efficiency of the cooler and increases emissions and pressure drop across the cooler. They may also be acidic and corrosive. Fouling has been always treated as an approximate factor in heat exchanger designs and it has not been modeled in detail. The aim of this paper is to look into fouling formation in an EGR cooler of a diesel engine. A 1-D model is developed to predict and calculate EGR cooler fouling amount and distribution across a concentric tube heat exchanger with a constant wall temperature. The model is compared to an experiment that is designed for correlation of the model. Effectiveness, mass deposition, and pressure drop are the parameters that have been compared. The results of the model are in a good agreement with the experimental data.

This paper presents experimental and simulation studies on a hydrogen fuel cell that utilizes hydrogen and oxygen as reactants, making it suitable for specific vehicles such as submarines and underwater vehicles with air-independent propulsion systems. A fuel cell prototype with an active area of 25 cm2 was constructed using commercial materials and analyzed in detail. The experimental data were compared to numerical results obtained by the ANSYS PEM Fuel Cell Module, and the two sets of results were found to agree closely across a range of polarization curve observations corresponding to voltages between 0.93 and 0.29 V. The validated numerical model enables exploration of internal phenomena, such as mass fractions, water contents, and current flux density that are difficult to study through experiments. This model can also aid in optimizing the configurations and characteristics of the fuel cell components.

The cooling system of Series Hybrid Electric Vehicles (SHEVs) is more complicated than that of conventional vehicles due to additional components and various cooling requirements of different components. In this study, a numerical model of the cooling system for a SHEV is developed to investigate the thermal responses and power consumptions of the cooling system. The model is created for a virtual heavy duty tracked SHEV. The powertrain system of the vehicle is also modeled with Vehicle-Engine SIMulation (VESIM) previously developed by the Automotive Research Center at the University of Michigan. VESIM is used for the simulation of powertrain system behaviors under three severe driving conditions and during a realistic driving cycle. The output data from VESIM are fed into the cooling system simulation to provide the operating conditions of powertrain components.